Penetration of water into wood is highly undesirable for a number of reasons. The water swells the wood and can cause grain raise which results in an uneven surface. Repeated wetting and drying can result in cracking of the wood due to the repeated swelling and contracting. The repeated swelling and contracting can also pop nails out of the wood. Penetration of moisture into the wood facilitates the growth of mildew and other organisms that can destroy the wood.
Prolonged exposure to a volatile organic compound ("VOC") can be hazardous to a person's health. Representative VOCs include solvents such as methyl ethyl ketone, trichloroethylene and the like.
Many water repellents have a relatively high VOC content due to the use of the VOC as a solvent. Government regulations are being phased in to limit the VOC content.
Water-based water repellents for wood often are not stable and therefore have a very short shelf life. The user of these water repellents can be required to add water just before use to compensate for the short shelf life. This is undesirable because it creates additional work for the user and can result in an improper amount of water being added or inadequate mixing.
Some water repellents form a coating on the wood which changes the wood's appearance. A change in appearance is highly undesirable, especially when using fine quality wood whose natural beauty is masked by the coating.
DuPont Chemicals manufactures a chrome complex solution under the trademark QUILON.RTM.. The brochure of April 1992, at page 5, indicates that salts of hydrochloric acid have little effect on solution solubility. The brochure at page 6 state that aqueous solutions of QUILON.RTM. prepared at room temperature remain stable for more than 24 hours at temperatures below 30.degree. C. (80.degree. F.). At 40.degree. C. (110.degree. F.) the working life shortens to 8 hours. These short time periods make QUILON.RTM. unsuitable for products that must be stable for a long time period. The brochure is silent as to the use of QUILON.RTM. as a wood preservative.
To reduce the VOC content in wood stains, manufacturers are developing water-based stains. However, these stains do not color evenly, as some sections of the untreated wood absorb more water, and hence more colorant, than others. The water-based stains are not conventionally used with water repellent treated wood.
A water repellent solution having a reduced VOC content and which has a long, stable shelf life and a preservative effect on wood is highly desirable.